Solid state watch with magnetic setting

ABSTRACT

Disclosed is a solid state electronic wristwatch with no moving parts. The watch electronics are hermetically sealed in the watch case to be free of dust and moisture and the sealed components are resiliently mounted for improved shock resistance. Two setting switches and a demand switch within the casing are operated from outside the watch by permanent magnets, the demand magnet operating with a demand pushbutton. The setting magnet may be stored in the watch bracelet.

United States Patent [1 1 Bergey [4 1 Jan. 1,1974

[54] SOLID STATE WATCH WITH MAGNETIC 3,509,7l5 5/1970 Dekoster 58/50SETTING 3,576,099 4/1970 Walton 553/23 R [75] Inventor: John M. Bergey,Lancaster, Pa. Primary Examiner Richard Wilkinson [73] Assignee: TimeComputer, Inc., Lancaster, Pa. AS81314"! EXdminer-Edith SimmOHS JaCkmO"Att0rney-Le Blanc & Shur [22] Filed: Apr. 29, 1971 [21] Appl. No.:138,557 [57] ABSTRACT Disclosed is a solid state electronic wristwatchwith no 52 us. Cl. 58/50 R, 58/85.5 moving P The Weteh eleetrenies erehermetically 511 int. Cl. G04b 19/30, G04b 27/00 sealed in the Wetehease to be free of dust and mele- [58] Field of Search 58/23, 23 R, 23A, We and the Sealed eempenems are resiliently 5 33 3 50 355, 200/56,60, 6159 mounted for improved shock resistance. Two setting switches anda demand switch within the casing are [56 References Cited operated fromoutside the watch by permanent mag- UNITED STATES PATENTS nets, thedemand magnet operating with a demand 3 672 55 6/1972 B gc ct a] 58/85 5X pushbutton. The setting magnet may be stored in the 3:643:41) 2/1972Motta] watch bracelet 3,129,557 4/1964 Ficchter 525/23 R X 5 Claims, 15Drawing Figures 26 30 Q 34 "l 28 F 32 FREQ. FREQ, gtffiw STANDARDCONVERTER V M EAN S PAIENTEDJAH H974 3782.102

sum-1o; 9

' IG JOHN- M. B SR ATTORNEYS.

PAIENTEDJAH I 1914 3.782.102

' I SHEET 2 (IF 9 FIG. 2

INVENTOR ATTORNEY-5'.

JOHN M. BERGEY DISPLAY INTENSITY CONTROL LIB - DISPLAY, ACTUATING MEANSIIIIIIIIIIIII MIN SET SET s4uz I F|G.3

'0 bcdefgh colon obcdefgubcdefg CONVERTER I 238 READ FIG.5

I IQ

FREQ. STANDARD III I 32.768 KHZ PATENTEDJAH 914 SREEI S 0F 9 INVENTORJOHN M. BERGEY ATTORNEYS.

PATENTEDJAH '1 m4 3.782.102 SHEET 70F 9 INVENTOR JOHN M. BERGEYATTORNEYS.

PATENTEDJAH 1 m4 3782.102

" sum ear 9 INVENTOR JOHN M. BERGEY ATTORNEYS.

PATENTEDJAH 1 I974 sum ear 9 FIG. l2

INVENTOR JOHN M. BERGEY xgw; Q

ATTORNEYS.

SOLID STATE WATCH WITH MAGNETIC SETTING This invention relates to asolid state timepiece and more particularly to an electronic wristwatchwhich employs no moving parts. In the present invention, a frequencystandard in the form of a crystal oscillator acts through solid stateelectronic circuit dividers and drivers to power in timed sequence thelight-emitting diodes of an electro-optic display. Low power consumptionand small size and weight are achieved through the use of complementaryMOS circuits to produce what is in essence a miniaturized fixed programcomputer. In particular, the present invention is directed to a solidstate wristwatch of this type in which the active components arecompletely sealed for longer life and which incorporates an improvedread switchmagnetic setting arrangement.

Battery-powered Wristwatches and other small portable timekeepingdevices of various types are well known and are commercially available.The first commercially successful battery-powered wristwatch is of thetype shown and described in assignees U.S. Reissue Pat. No. Re 26,187,reissued Apr. 4, 1967, to John A. Van Horn et al. for ELECTRIC WATCH.Electric watches of this type employ a balance wheel and a hairspringdriven by the interaction of a current-carrying coil and a magneticfield produced by small permanent magnets.

In recent years, considerable effort has been directed toward thedevelopment of a wristwatch which does not employ an electromechanicaloscillator as the master time reference. In many instances, theseconstructions have utilized a crystal-controlled high frequencyoscillator as a frequency standard in conjunction with frequencyconversion circuitry to produce a drive signal at a suitable timekeepingrate. However, difficulties have been encountered in arriving at anoscillatorfrequency converter combination having not only the requiredfrequency stability but also sufficiently low power dissipation andsmall size to be practical for use in a battery-powered wristwatch.

In order to overcome these and other problems, there is disclosed inassignees US. Pat. No. 3,560,998, issued Feb. 2, 197], acrystal-controlled oscillator type watchconstruction using low powercomplementary MOS circuits. The oscillator-frequency convertercombination of that patent is described as suitable for drivingconventional watch hands over a watch dial or, alternatively, forselectively actuating the display elements of an optical display inresponse to the drive signal output of the converter.

In assignees U. S. Pat. No. 3,576,099, issued Apr, 27, 1971 there isdisclosed an improved watch construction in which the optical displaytakes the form of a plurality of light-emitting diodes which areintermittently energized on demand at the option of the wearer of thewatch. This assures a minimum power consumption and an increasingly longlife for the watch battery. An improved watch construction of thisgeneral type incorporating solid state circuits and integrated circuittechniques is disclosed in assignees copending U. S. Pat. applicationSer. No. 35,196, filed May 6, 1970, now US. Pat. No. 3,672,l55.

The present invention is directed to an improved watch construction ofthe same general type as disclosed in the aforementioned application andpatents and one which utilizes no moving parts to perform thetimekeeping function. The watch of the present invention consists ofthree major components, namely, a quartz crystal time base, a miniaturetime computer module, and a power supply or battery. Thesemicrominiature components are packaged in a conventional size wristwatchchassis or case. Atiny quartz slab is precisely cut to predetermineddimentsons so that it vibrates at 32,768 Hz when properly stimulated bypulses from an electronic oscillator. The high frequency from thecrystal time base is divided down to 1 pulse per second by utilizing amulti-stage integrated circuit binary counter. The time computer modulecounts thepulse train, encodes it into binary form, and then decodes andprocesses the result so as to provide the appropriate signals at displaystations.

Situated on the front of the watch adjacent the display is a pushbuttondemand switch which, when pressed, instantly activates the appropriatevisual display stations. Minutes and hours are programmed to display forone and one-quarter seconds, with just a touch of the demand switch.Contined depression of this switch causes the minute and hour data tofade and the seconds to immediately appear. The seconds continue tocount as long as the wearer interrogates the computer module.Computation of the precise time is continuous and completely independentof whether or not it is displayed.

The watch display consists of a television screen-like colored filterwhich passes the cold red light from gallium arsenide phosphide (GaAsP)light-emitting diodes. Preferably a seven segment array forms eachindividual number at the appropriate moment at a brightness determinedby a specially constructed dimmer or display intensity control circuit.This dimmer circuit utilizes one or more photodetectors to measureambient lighting conditions so the display intensity provides viewingcomfort under all day or nighttime lighting conditions.

Important features of the present invention include a magneticallyoperated demand or read switch and magnetically operated hour set" andminute set switches for setting the watch to the appropriate time. Thehour set switch rapidly advances the hours without disturbing theaccuracy of the minutes or seconds. The minute set switch automaticallyzeros the seconds while it advances the minutes to the desired setting.The whole procedure, even though seldom required, takes a matter of afew seconds.

Because of the magnetic setting and magnetic interrogation, activecomponents of the watch may be hermetically sealed to produce a unitthat is shockproof and waterproof, regardless of the environment inwhich it is placed. Since there is no conventional stem for winding orsetting, the small shaft sealing problem is eliminated and nomaintenance or repair is normally necessary since the active componentsare hermetically sealed and inaccessible to influences from the outsideworld. All solid state electronic components, includingthelight-emitting diode displays, have a virtually unlimited life.

It is therefore one object of the present invention to provide animproved electronic wristwatch.

Anotherobject of the present invention is to provide a wristwatch whichutilizes no moving parts for performing the timing function.

Another object of the present invention is to provide a solid statewatch in which the active components of the watch are hermeticallysealed.

Another object of the present invention is to provide a magneticallyoperated on demand display system for a solid state watch.

Another object of the present invention is to provide a solid statewristwatch incorporating magnetic time setting.

Another object of the present invention is to provide a solid statewristwatch having a digital optical display which is virtuallyshockproof and 'waterproof.

Another object of the present invention is to provide a solid statewristwatch with no moving parts having improved operatingcharacteristics and reduced cost.

These and further objects and advantages of the invention will be moreapparent upon reference to the following specification, claims, andappended drawings, wherein:

FIG. 1 is a front view of a conventional size mans wristwatchconstructed in accordance with the present invention;

FIG. 2 is a simplified block diagram of the major components of thesolid state watch of this invention;

FIG. 3 shows a display element for the watch of the present invention inthe form of a seven bar segment construction of light-emitting diodes;

FIGS. 4, 4a, and 4b, taken together, are an overall block diagram of theelectrical circuit for the solid state watch of FIG. 1;

FIG. 5 shows a modified watch circuit in which substantially all of themajor electrical components of the watch are formed using large-scaleintegrated circuitry; FIG. 6 is an exploded view of the wristwatch ofFIG.

FIG. 7 is a cross section taken along line 66 of FIG. 1;

FIG. 8 is a bottom plan or rearview of the watch of FIG. 1;

FIG. 9 is a cross section perpendicular to that of FIG. 7 taken alongline 9-9 of FIG. 1;

FIG. 10 is an enlarged plan view of the demand button assembly of thewatch of FIG. 1;

FIG. 11 is a cross section through the demand button assembly takenalong line ll--ll of FIG. 10;

FIG. 12 is a cross section perpendicular to that of FIG. 11 taken alongthe line 12-l2 of FIG. 10; and

FIG. 13 is a plan view of the flat demand button spring before it isformed into the curved shape shown in FIGS. 11 and 12.

Referring to the drawings, the novel watch of the present invention isgenerally indicated at 10 in FIG. 1. The watch is constructed to fitinto a watch case 12 of approximately the size of a conventional manswristwatch. The case 12 is shown connected to a wristwatch bracelet l4and includes a display window 16 through which time is displayed indigital form as indicated at 20. Mounted on the case 12 is a demandswitch pushbutton 18, by means of which the display 20 may be actuatedwhen the wearer of the wristwatch 10 desires to ascertain the time.

In normal operation, time is continuously being kept but is notdisplayed through the window 16. That is, no time indication is visiblethrough the window and this is the normal condition which prevails inorder to conserve battery energy in the watch. However, even though thetime is not displayed through the window 16, it is understood that thewatch 10 continuously keeps accurate time and is capable of accuratelydisplaying this time at any instant. When the wearer desires toascertain the correct time, he depressed the pushbutton 18 with hisfinger and the correct time is immediately displayed at 20 through thewindow 16. The hours and minutes are displayed through the window 16 fora predetermined length of time, preferably 1% seconds, irrespective ofwhether or not the pushbutton 18 remains depressed. The exact time ofthe display is chosen to give the wearer adequate time to consult thedisplay to determine the hour and minute of time. Should the minuteschange during the time of display, this change is immediately indicatedby advancement of the minute reading to the next number as the watch isbeing read. If the pushbutton 18 remains depressed, at the end of 1%seconds, the hours and minutes of the display are extinguished, i.e.,they disappear, and simultaneously the seconds reading is displayedthrough the window 16 immediately below the hours and minutes display20. The advancing seconds cycling from 0 to 59 continue to be displayedthrough window 16 until pushbutton switch 18 is released.

FIG. 2 is a simplified block diagram of the principal components of thewatch 10 of FIG. 1. The circuit comprises a time base or frequencystandard 26 including a piezoelectric crystal to provide a very accuratefrequency such that the frequency standard or oscillator oscillates at32,768 Hz. This relatively high frequency is supplied by a lead 28 to afrequency converter 30 in the form of a divider which divides down thefrequency from the standard so that the output from the converter 30appearing on lead 32 is at a frequency of 1 Hz. The frequency converter30 preferably comprises a binary counting chain of complementary MOStransistors of the type shown and described in assignees U.S. Pat. No.3,560,998, the disclosure of which is incorporated herein by reference.The 1 Hz signal is applied by lead 32 to a display actuator 34 which inturn drives the displays 20 and 22 of the watch 10 by way of electricallead 36.

FIG. 3 shows a display station 38 forming one of the numerals of thehours and minutes display 20 and the seconds display 22. Each of thesedisplay stations (with the exception of the hours tens display as morefully described below) is preferably in the form of a seven bar segmentarray of light-emitting diodes of the type shown and described in detailin assignees U.S. Pat. No. 3,576,099, issued Apr. 27, 1971, thedisclosure of which is incorporated herein by reference. FIG. 3 showsseven bar segments of light-emitting diodes 40, 42, 44, 46, 48, 50, and52, all of elongated shape and arranged so that by lighting anappropriate combination of the bars or segments any of the numbers 0through 9 may be displayed.

FIGS. 4, 4a, and 4b show an overall block diagram of the electricalcircuit of the watch of the present invention. Reference may be had toassignees copending U.S. Pat. application Ser. No. 35,196, filed May 6,1970 now U.S. Pat. No. 3,672,155, the disclosure of which isincorporated herein by reference, for a detailed description of theconstruction and operation of the electrical circuit. Briefly, however,and referring to the overall block diagram of FIGS. 4, 4a, and 4b, thewatch 10 comprises an oscillator 96 which is controlled by a crystal toproduce an output on lead 98, i.e., a pulse train on that lead having apulse repetition rate of 32,768 Hz. The crystal output passes through acomplementary symmetry MOS counter 100 of the type shown and describedin assignees US. Pat. No. 3,560,998, which acts as a divider, dividingthe output by 2, i.e., a seven stage counter, to produce an output onlead 102 having a pulse repetition rate of 256 Hz. This signal isdivided by 2 in counter 104, by 2 again in counter 106, by 8 (2) incounter 108, and by 4 (2 in counter 110.

An 8 Hz output on lead 112 from counter 108 is applied to a set-holdcircuit 114 where the 8 Hz repetition rate pulse train appears as anoutput on lead 116. The 8 Hz signal on lead 116 is applied to a counter118 where it is divided by 8 (2") to produce a 1 Hz output pulse trainon lead 120. The 1 Hz pulse train is divided by l0 in counter 122,divided by 6 in counter 124, divided by again in counter 126, divided by6 in counter 124, divided by 10 again in counter 126, divided by 6 againin counter 128, and the output of this counter is finally applied tocounter 130 which divides by 12. The output of counter 122 appearing onleads 132, 134, 136, and 138 is a binary coded decimal 1248 code whichis applied to the decoder-driver 140 which, in turn, energizes the tensdigits of the seconds display indicated at 142. The ones digits of theseconds display indicated at 144 are similarly actuated from counter 124by way of seconds decoder-driver 146. Similar decoder-drivers 148, 150,and 152 actuate the tens digits of the minutes display at 154, the onesdigits of the niinutes display at 156, and the hours display at 158.Counter 130 has five output leads to decoder-driver 152 for a purposemore fully described below. The other decoder-drivers 146, 148, and 150are actuated by BCD 1248 codes from their respective counters 124, 126,and 128 in the same manner as decoderdriver 140 is actuated from counter122.

As previously stated, in order to conserve energy, the light-emittingdiodes are only energized on demand, i.e., when the pushbutton 18 ofFIG. 1 is depressed by the wearers finger. Even when the button isdepressed, the lights are not always continuously lit but instead, inorder to conserve power, are intermittently lighted during less thanfull daylight conditions at a frequency sufficiently high to give theappearance of continuity due to the light retention properties of thehuman eye. The pulses for intermittently lighting or pulsing the secondsdisplay are derived from a display control driver 160 which applies theON-OFF pulses by way of lead 162 to the seconds decoder-drivers 140 and146. Similar intermittent pulses from the display control drivers 160are applied by lead 164 to the minutes decoder-drivers 148 and 150 andby lead 166 to the hours decoder driver 152. The exact frequency atwhich the displays are turned on and off while always sufficiently highto give the impression to the human eye of continuous light isdetermined by a light control circuit 168 which supplies a light controlsignal over lead 170 to display control drivers 160. The light controlsignal is either DC (full daylight) or a combination of a 64 Hz signalsupplied from counter 106 by way of lead 172, a 128 Hz signal suppliedby counter 104 by way of lead 174, and a 256 Hz signal supplied from theoutput of counter 100 by way of lead 176. These signals are combined inthe light control circuit 168 in a manner determined by the outputsignal on lead 178 to the light control circuit from ambient lightsensors 180. These light sensors are in the form of threephoto-transistors mounted on the face of the watch inside the viewingwindow and act to produce increased illumination from the light-emittingdiodes during strong daylight conditions and less illumination from thediodes under nighttime or reduced light conditions. In the preferredembodiment, light sensors 180 provide four different light levels fromthe light-emitting diodes so that the watch face may be read with equalfacility and comfort under all possible lighting conditions, while atthe same time conserving energy at times when less light is needed fromthe diodes to make them visible, such as is the case when the watch isread in at least partial darkness.

As previously stated, the watch face is ordinarily not illuminated. Thehours and minutes diodes only light up when the demand switch isdepressed. Actuation of the demand button by the wearer causes the readswitch 184 in FIG. 4 to close, causing the positive side of the powersupply to be connected by way of leads 186 and 188 to the displaycontrol drivers 160. Energization of these drivers permits passagethrough them of the signal from the light control circuit 168 which ispassed on to the decoder-drivers causing the minutes and hours displaysto be illuminated. No'output from the display control diodes 160 appearson lead 162 at this time and the seconds displays are not illuminated.Closure of the read switch 184 also applied B+ by way of lead 190 toset-hold circuit 114 which immediately resets a display timer 192 by wayof lead 194. Display timer 192 is a divide by 10 counter and has appliedto its input the 8 Hz pulse train on lead 112. This timer divides the 8Hz pulse by 10 and after 1% seconds produces an output pulse on lead 196which is applied to display control driver 160. This pulse causes thedisplay control driver to change state, removing the output from leads164 and 166 and causing the minutes and hours display to beextinguished. At the same time, the output is switched to lead 162causing the seconds display to be illuminated simultaneous with theextinguishment of the hours and minutes display.

An important feature of the watch of the present invention lies in thefact that the hours may be set independently of the minutes and secondsand at a very rapid rate. Closure of hours-set switch 198 grounds oneinput of an hours-set circuit 200 by way of leads 202 and 204. Hours-setcircuit 200 receives a 2 Hz pulse train from counter by way of lead 206and actuation of the hours-set circuit by closure of hours-set switch198 causes the hours-set circuit 200 to pass the 2 Hz signal on lead 206to counter by way of lead 208. Hours-set switch 198 is also connected tothe display control drivers to cause an output to appear on leads 164and 166 assuring that the hours and minutes are displayed when the hoursare being reset during closure of switch 198. A minute-set switch 212 isconnected by leads 214 and 216 to a minute-set circuit 218. As before,actuation of this circuit causes it to pass a 2 Hz pulse train on lead220 from counter 110 by Way of lead 222 to the divide by 10 counter 126driving the minutes display. Minute-set switch 212 is likewise connectedby lead 224 to display control drivers 160, again to insure an output onleads 164 and 166 during resetting. In the watch of the presentinvention, actuation of the minute-set switch 212 automatically zerosthe seconds display. The reason for this is that most time signals, suchas those given over the radio and the like, are given on the hour or onthe minute and in order to start the watch in synchronism with thecorrect time as given by such a signal, it is necessary that the secondsdisplay be at zero at the time the radio tone or other time signal isheard. In order to accomplish this, the minute set switch 212 isconnected by leads 214 and 216 and a further lead 226 to set-holdcircuit 114. Energization of this circuit from lead 226 produces anoutput pulse on output lead 228 which is applied to the reset terminalsof counters 118, 122, and 124 by way of leads 229, 231, and 233,resetting these counters to zero and causing the seconds display to beautomatically zeroed. Depressing read switch 184 unlocks the set timeand begins the real time counting sequence.

FIG. shows a modified embodiment of the solid state watch of the presentinvention, generally indicated at 230. In FIG. 5, like parts bear likereference numerals, and the overall construction of the watch in FIG. 5is generally similar to the embodiment previously described. Theprincipal modification incorporated in the embodiment of FIG. 5 is thatthe vast ma jority of the electrical components are formed from one ormore large-scale integrated circuits, as indicated by the largeintegrated circuit block 232 in FIG. 5. Reference may be had toassignees copending United States patent application Ser. No. 138,547,filed Apr. 29, I971, now US. Pat. No. 3,714,867 and entitled SOLID STATEWATCH INCORPORATING LARGE- SCALE INTEGRATED CIRCUITS, in the name ofBruno M. Dargent, for a detailed description of the large-scaleintegrated circuit 232, the disclosure of that copending applicationbeing incorporated herein by reference.

In FIG. 5, the crystal oscillator 96 is of the type previously describedand includes a piezoelectric crystal 234, a variable trimming capacitor236, and a bias resi'stor 238. The active components of the oscillatorare a pair of complementary MOS transistors connected to form aninverter and they are incorporated in the largescale integrated circuit232. As in the previous embodiment, the oscillatoi preferably operatesat a frequency of 32,768 Hz. The entire watch is powered from aconventional watch battery or power supply, indicated at 240, and thedemand switch 184, the minute-set switch 212, and the hour-set switch198 are all connected from the positive side of the battery 240 to theother or grounded side of the battery through the respective resistors242, 244, and 246.

The modified embodiment in FIG. 5 includes a modified dimmer or displayintensity control circuit comprising a capacitor 248, a resistor 250, alight sensitive resistor 252, a second resistor 254, and a secondcapacitor 256. These components in effect form a multivibrator which istriggered at a frequency of 64 Hz, which trigger signal is derived froman intermediate stage of the divider or frequency converter 30incorporated in the large-scale integrated circuit 232. The pulse widthof the multivibrator and therefore the duty cycle of the output from themultivibrator depends primarily on the value of fixed capacitor 256 andthe value of the variable light sensitive resistor 252. For decreasingamounts of ambient light impinging upon resistor 252, as indicated bythe arrow 258, the duty cycle of the multivibrator output is reduced andthis output signal is applied to the displays and 22 so as to vary theirintensity with the amount of ambient light, i.e., the intensity isincreased when the ambient light is great and the intensity of thelight-emitting diodes is reduced when ambient light decreases.

The displays are controlled from the large-scale integrated circuit 232by a pair of bipolar switches 260 and 262, labeled S, and Srespectively. These transistors connect the cathodes of thelight-emitting diodes of the display to the negative side of the battery240, i.e., to ground, so that the circuit to the light-emitting diodesis completed when the transistors 260 and 262 are in conduction. Thesetransistors have their bases connected to the large-scale integratedcircuit 232 through respective resistors 264 and 266. It is understoodthat when one of the switches S, or S is turned on, the other is off andvice versa so that all displays are not simultaneously on. When switchS, (260) is turned on, this completes the circuit to the hours andminutes display diodes 20. If the demand button remains depressed, after1% seconds switch 260 is turned off by the largescale integrated circuit232 and switch 262 is simultaneously turned on so that the hours andminutes display 20 disappears and the seconds display 22 immediatelycomes on. These displays receive timing signals from the large-scaleintegrated circuit 232 through the connecting leads generally indicatedat 268.

FIG. 6 is an exploded view of the watch and FIG. 7 is a cross sectionthrough the watch of the present invention taken along line 7-7 ofFIG. 1. The watch case 12 comprises a front plate 270, an inner cover272, and a removable back plate 274. These three plates are preferablymade from a non-magnetic metal material, such as that sold under thetrade name Haver. Between inner cover 272 and back plate 274 is thepower supply in the form ofa pair of 1.5 volt dry cells 276 and 278. Thecells are preferably silver oxide batteries and are connected in seriesto produce an operating voltage of about 2.5 to about 3.2 volts DC. Backplate 274 carries a plurality of mounting springs 280 with projections282 which snap into corresponding recesses in the front plate 270 forready attachment and removal of the back plate so that access may begained to the battery cells 276 and 278. The back plate is sealed by anannular rubber O-ring 284.

FIG. 8 is a bottom plan or rear view of the watch of FIG. 1 withportions shown in dashed lines and FIG. 9 is a cross section at rightangles to the cross section of FIG. '7 taken along line 9-9 of FIG. 1.FIG. 10 is an enlarged plan view of the assembly for demand button 18.The battery cells are separated from back plate 274 by annularinsulating washers 284 but have their negative side connected to theback plate and therefore grounded to the case by an electricallyconductive cell connector 286. A similar cell connector 288 (FIG. 9)connected to the positive side of the power supply is electricallyconnected to a positive cell lead 290 which passes through a suitableglass seal 292 to establish electrical connection to the electroniccircuit indicated generally at 294 mounted on circuit substrate 296.Trimming capacitor 236 and the piezoelectric crystal 234 are alsomounted on the substrate 296. Placed in the viewing window over thelight-emitting diodes is a light filter 298. The filter is fabricatedfrom a ruby to insure relative scratch and break resistance. Asolderable metal material is deposited along the edge of the filter toaid in the solder-sealing of the filter to the front plate 270 asindicated at 300 in FIG. 9. The pink ruby is preferably coated with ared dyed clear epoxy paint on its inside surface to provide a deep redcolor which transmits most of the 6,500 Angstrom wavelength light fromthe light-emitting diodes carried by the electronic substrate 296. Innercover 272 is solder-sealed to front plate 270 around its edge, asindicated at 302 in FIG. 9, and this inner cover carries four mountingposts, two of which are illustrated at 304 in FIG. 9. These posts orstuds are welded to inner cover 272 and the substrate 296 is heldagainst these shoulder studs by means of screws 306. Both sides of thesubstrate rest against a resilient shock absorbent material 308 and 310to provide maximum protection against severe shocks encountered whendropping the watch. The crystal can 234 and trimming capacitor 236 areall similarly protected by soft potting compound between the substrateand their assembled position as indicated at 312 and 314, respectively.I

As can be seen, the electronics 294 is hermetically sealed all the wayaround between inner cover 272 and front plate 270. This hermetic sealacts as protection to the electronics and also prevents condensation ofwater vapor on the filter 298. The hermetically sealed cavity isprovided by solder-sealing the filter to the front plate andsolder-sealing the inner cover to this plate. The battery compartment isoutside this cavity and is protected from the outside world by the caseback or back plate 274 and the O-ring gasket 284. Electrical connectionsof the battery to theelectronics are provided by glass-to-metal sealedfeedthrough connectors as indicated at 292.

An important feature of the present invention resides in the fact thatthe read or demand switch 184, the minute-set switch 212, and thehour-set switch 198 are all magnetically operated in such a way that theelectronics 294 remains hermetically sealed. These three switches areshown in dashed lines in FIG. 8 and are preferably in the form of reedswitches. There are several significant advantages in utilizing apermanent magnet operated reed switch to perform the hours, minutes anddemand readout functions in the watch. First, the miniature switches areglass encapsulated, hermetically sealed devices which have a provenhistory of high reliability in this type of application. Secondly, nothrough-holes are required in the watch case so true hermetic sealing issimplified. Also, actuation of the switches requires a' deliberateactivity on the part of the wearer so that inadvertent operation isminimized. These switches are positioned in the watch as illustrated inFIG. 8 and attached to the substrate 296 by a soft potting compound, asillustrated, for example, at 316 in FIG. 9 for the hours-set switch 198.These switches are preferaby of the type identified as MINI-2 switchesmanufactured by Hamlin, Inc. of Lake Wills, Wis., or equivalent. Aswitch pull sensitivity of between l and '20 ampereturns is desirablefor the demand switch, while 35 to 40 ampereturns is desirable for boththe hour and minutes set switches.

As best seen in FIG. 8, the front plate 270 of the watch case isprovided with a first elongated setting slot 318 adjacent hour-setswitch 198 and a second setting slot 320 adjacent the minute-set switch212. A portion of the setting slot 318 is illustrated in solid lines inFIG. 9. Itis understood that the minute-set switch slot or recess 320 isof similar construction. These two recesses or slots, one adjacent thehour-set switch and the other adjacent the minute-set switch aredimensioned so that a long cylindrical or square magnet can be placedinto this recess when a change in setting time is desired. In

the preferred embodiment, the setting magnet takes the form of apermanent magnet made from Alinco V material'with dimensions of 0.500inch long by 0.062 inch square. This produces a field of about 700gauss.

As best seen in FIG. 7, the demand switch 184 is supported from thesubstrate 296 in a manner similar to the other switches, i.e., by a softpotting compound as illustrated at 322. FIG. 10 is a plan view of thepushbutton assembly 18, FIG. 11 is a cross section through thepushbutton assembly taken along line 11-11 in FIG. 10, FIG. 12 is across section at right angles to that of FIG. 11 taken along line 12-l2of FIG. 10, and FIG. 13 shows the flat pushbutton spring before it isformed into a curved spring shape.

The pushbutton assembly is constructed so as to retain the hermetic sealabout the electronic components of the watch. The pushbutton assemblycomprises an elongated pushbutton proper 324 slidably received through asuitable aperture 326 in the front plate 270 of the watch case. Pressfit into a circular recess in the center of the pushbutton 324 is apermanent magnet 328 formed in the shape of a right circular cylinder.Recess 326 is stepped to form a shoulder 330 which cooperates with anannular flange 332 on the lower end of pushbutton 324 to limit theupward or outward movement of the pushbutton. The plate shoulder 330 andannular flange 332 are preferably separated by an annular gasket 334made of silicone.

The inner end of aperture 326 is closed off by a flat rectangular plate336 made of brass or other suitable non-magnetic material. Brass plate336 is soldered for a hermetic seal all the way around its edge to theinner surface 338 of front plate 270 as indicated at 340 in FIGS. 11 and12. In this way, the pushbutton 324 and magnet 328, while mounted on thefrontplate, are sealed externally of the chamber carrying the watchelectronics. Resting on top of brass plate 336 is a substantiallyrectangular arched or curved spring 342 which urges the pushbutton 324and the magnet 328 carried by it upwardly or outwardly in the directionof the arrow 344 in FIG. 11. Spring 342 is preferably made of Havar orother suitable non-magnetic metallic material and, while its ends 346and 348 rest on top of brass plate 336, it is symmetrically curved orarched about the centerline 350 of the pushbutton assembly so that itscenter is spaced approximately 0.030 inch from the top of brass plate336. FIG. 13 shows the Havar spring 342 in plan view while it is flatand before it is formed into the arched or curved configurationillustrated in FIGS. 11 and 12. By way of example only, the spring mayhave a thickness of approximately 0.0024 inch. The demand magnet 328which is press fit into the recess in pushbutton 324 is about 0.070 inchlong and about 0.090 inch in diameter and utilizes cobalt platinum(CoPt) to produce a field of about 1,300 gauss.

It is apparent from the above that the present invention provides animproved timepiece construction and particularly a timepiece havingsufficiently small size, weight and power consumption for use as aconventional man s wristwatch. Important features of the presentinvention include a resilient shock-free mounting arrangement, acompletely hermetically sealed assembly so that the electronics, displayand other major components are completely sealed from atmosphericeffects, a magnetically operated demand or read switch, and a pair ofmagnetically operated setting switches for setting the watch time. Thesetting permanent magnet may conveniently be stored in a suitable recessin the watch bracelet when not in use or may otherwise be carried on oradjacent the watch or in a suitable recess provided in the watch case.If desired, it is possible to paint the substrate and light reflectingmaterials in the vicinity of the light-emitting diodes a dark flatblack. This improves readout visibility by providing maximum contrastratio between the lightemitting diodes and their background. Thepiezoelectric crystal for the oscillator is preferably contained in itsown hermetically sealed vacuum can to reduce its series resistance,improve its activity for any given drive current, and to minimize thenatural aging effects of the crystal. In the preferred embodiment, thepower supply is formed of two silver oxide cells in a standard sizecontainer operating at a nominal voltage of about 3 volts, but it isunderstood that any conventional wristwatch power supply may beutilized. As illustrated in FIG. 7, the electrical cells 276 and 278 arepreferably mounted in a cell holder 352 mounted on the outside orbackside of inner cover 272.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

l. A wristwatch comprising a watch case of nonmagnetic material,timekeeping means in said case including a solid state electroniccircuit and an electrooptic digital time display, a pushbutton on saidcase, a magnetic field responsive switch in said case for controllingsaid display, and a permanent magnet movable with said pushbutton toactivate said switch when said pushbutton is in a first position anddeactivate said switch when said pushbutton is in a second position.

2. A wristwatch according to claim 1 wherein said case includes anaperture, said pushbutton being mounted for reciprocation in saidaperture, said permanent magnet being mounted in said pushbutton, meansresiliently biasing said button and magnet in an outward direction, andmeans closing off and sealing the inner end of said aperture.

3. A wristwatch according to claim 2 wherein said switch comprises areed switch located in said case adjacent the closed end of saidaperture.

4. A wristwatch according to claim 1 including means resilientlymounting said circuit and said display in said case.

5. A wristwatch according to claim 1 wherein said timekeeping meanscomprises a source of constant frequency electrical signals, a dividercoupled to said source, a display actuator coupled to said divider, anda plurality of light-emitting diodes coupled to said display actuator.

Wm UMT'JJ) STATES PATENT. 'OFFECE r? I 1 w-v r \r Y. CEK- I 1 ."iCA l EO CQHHEIC l LO'N Patent 5:0. 3,782,102 Dated Januagj 1. 1974'lnventofls) John M. Bergey Itfis certified that rror appears in theabove-identified patent and that said Letteqcs Patent are herebycorrected as shown below:

Col. 2, 1ine 12, "thepulse" should read --the pulse--; line 21,."Contined" "should read '-Cor 1tinued line 59, "thelight" should read"the light".

Signed and rsjeial e d this 11pm day of May 1971;. v

. (SEAL) Atte st:

EDWAR M.FLET 3HER,JR. I c. MARSHALL DANN Attestlng Officer I I JCommissioner. of Patents "Hg-f UmTli-n STEATIES ATER}? "OFFICCERTIFECATE 9F CORBE, "UQON Patent No. 3,782,102 Dated January 1. 1974inventor) ohn M. Bergey It is certified that rror appears in theabove-idefitified patent and that said Letters Patent are herebycorrected as shown below:

Col, 2, line 12, "thepulse" should read --the pulse--; line 21,"Contined" should read --Continued--; line 59, "thelight" should read--the light--..

Signed and ,s e al e d this lLtth day of May 197M.

.(SEAL) Attest:

EDWARD MJLETCHER, JR. I C MARSHALL DANN Attes'ting Officer ICommissionergof Patents

1. A wristwatch comprising a watch case of non-magnetic material, timekeeping means in said case including a solid state electronic circuit and an electro-optic digital time display, a pushbutton on said case, a magnetic field responsive switch in said case for controlling said display, and a permanent magnet movable with said pushbutton to activate said switch when said pushbutton is in a first position and deactivate said switch when said pushbutton is in a second position.
 2. A wristwatch according to claim 1 wherein said case includes an aperture, said pushbutton being mounted for reciprocation in said aperture, said permanent magnet being mounted in said pushbutton, means resiliently biasing said button and magnet in an outward direction, and means closing off and sealing the inner end of said aperture.
 3. A wristwatch according to claim 2 wherein said switch comprises a reed switch located in said case adjacent the closed end of said aperture.
 4. A wristwatch according to claim 1 including means resiliently mounting said circuit and said display in said case.
 5. A wristwatch according to claim 1 wherein said timekeeping means comprises a source of constant frequency electrical signals, a divider coupled to said source, a display actuator coupled to said divider, and a plurality of light-emitting diodes coupled to said display actuator. 